Department of Medical Microbiology, Postgraduate Institute of Medical Education & Research, Chandigarh, India.
Department of Internal Medicine, Postgraduate Institute of Medical Education & Research, Chandigarh, India.
Indian J Med Res. 2020 Jan;151(1):59-64. doi: 10.4103/ijmr.IJMR_92_18.
BACKGROUND & OBJECTIVES: In India, spotted fever group rickettsiae (SFGR) are an underdiagnosed cause of acute febrile illness (AFI). The non-specific Weil-Felix test is the first diagnostic modality for the diagnosis of SFGR in many laboratories due to the lack of advanced diagnostic facilities in developing countries. The aim of this study was to detect SFGR using molecular methods in the patients, presenting with AFI in a tertiary care centre in north India.
Consecutive patients (>14 yr of age) with AFI were enrolled over a six month period. Standard investigations for common pathogens causing AFI in India (malaria, dengue, scrub typhus, leptospirosis and enteric fever) were carried out. In patients who were negative for all of the above investigations, blood was subjected to polymerase chain reaction (PCR) targeting outer membrane protein A (ompA) gene of Rickettsia.
Of the 51 patients with an undiagnosed aetiology, three were positive by ompA PCR. Two of the PCR products produced good sequences and BLAST identification confirmed them as Rickettsia conorii. The sequences of R. conorii reported from south India clustered with two previously reported novel rickettsial genotypes. The study sequences clustered in a group different from that of Rickettsia spp. of the south Indian sequences reported earlier.
INTERPRETATION & CONCLUSIONS: This study showed the existence of R. conorii in north India. Testing for SFGR may be included in the diagnostic workup of AFI for better disease management.
在印度，斑点热群立克次体（SFGR）是一种被低估的急性发热性疾病（AFI）病因。由于发展中国家缺乏先进的诊断设施，非特异性魏尔-费利克斯试验是许多实验室诊断 SFGR 的首选诊断方法。本研究旨在使用分子方法在印度北部一家三级护理中心就诊的 AFI 患者中检测 SFGR。
在六个月的时间里，连续纳入患有 AFI 的年龄大于 14 岁的患者。对印度常见引起 AFI 的病原体（疟疾、登革热、丛林斑疹伤寒、钩端螺旋体病和肠热病）进行标准检查。在上述所有检查均为阴性的患者中，采集血液进行针对立克次体外膜蛋白 A（ompA）基因的聚合酶链反应（PCR）。
在 51 例病因不明的患者中，3 例通过 ompA PCR 阳性。其中两个 PCR 产物产生了良好的序列，BLAST 鉴定证实它们是康氏立克次体。从印度南部报告的康氏立克次体序列与之前报道的两种新型立克次体基因型聚类。研究序列与之前报道的印度南部立克次体属的序列聚类不同。
本研究表明印度北部存在康氏立克次体。在 AFI 的诊断中，可能需要检测 SFGR，以更好地进行疾病管理。
